Benson Henderson, like many who grew up in the Puget Sound area, has nostalgic memories of KeyArena.

Henderson, who grew up in Federal Way, used to love watching the Sonics. Gary Payton was his favorite player, which seems appropriate — with the nickname “The Glove” and his trash-talking persona — for a fighter like Henderson.

The Sonics, of course, have left town. And Henderson? Well, he’s gone from wrestling standout at Decatur High School to Ultimate Fighting Championship lightweight champion. He’ll headline UFC on FOX 5 Saturday at — where else? — a sold-out KeyArena.

“I used to watch the Sonics … and I could have never imagined fighting down on that arena floor,” Henderson said.

The 29-year-old will put his belt on the line against the top contender in the loaded 155-pound lightweight class, Nate Diaz. It’s the main event on a card that also features mixed martial arts legends BJ Penn and Mauricio “Shogun” Rua.

Some are calling it the best lineup UFC has assembled this year, and the crowd favorite will be no secret.

During open workouts Wednesday, Henderson was cheered on by excited fans, some of whom waited hours for an autograph or picture with the personable champ. Even an alum of Federal Way High — Decatur’s fiercest rival — offered support.

“It’s very exciting to fight not only in front of my family, but my friends and my old high-school classmates,” said Henderson, who boasts a 17-2 professional record, 5-0 in UFC.

“I’ve had a fair share of ticket requests. All my cousins and my cousins’ cousins and my cousins’ cousins’ cousins are all like, ‘You got any tickets for me?’ UFC only gives me four. Sorry.”

The biggest fight of Henderson’s career will also be his biggest challenge.

Diaz, a brash, talented 27-year-old, has won three fights in a row, two by impressive submission, since moving down from welterweight (170-pound limit). Diaz, one of UFC’s bad boys, won the fifth season of The Ultimate Fighter, a reality show, and his older brother, Nick, is a world-class fighter.

“I have a lot of respect for Benson Henderson and what he has done in his career,” Diaz told Yahoo! Sports. “But he’s what I call a round-winner. That’s not me. I am a fighter.”

Diaz (16-7, 11-5 UFC) added he felt Henderson should’ve lost his last fight, a controversial decision over Frankie Edgar in a title-fight rematch in August.

Henderson’s response is as carefree as his long, flowing hair.

“Everyone has their opinion,” he said. “Some people think that the moon landing wasn’t real. … Who am I to say, ‘Oh, yeah, your opinion is wrong.’ You can think whatever you want to think. It’s cool.”

It’s no wonder Henderson’s nickname is “Smooth,” a monker he lives up to in the ring.

The southpaw has won 15 of his past 16 bouts heading into his second UFC title defense. Athletic and resilient, he has never tapped out in his opponents’ 28 submission attempts.

Five straight wins by decision have led to criticism, however, that he can’t finish fights.

“This is the fight for him right here,” UFC president Dana White said. “Nate Diaz is mean and nasty and comes out and finishes people by knockout, by submission. I think this is the fight for Ben Henderson.

“If Ben Henderson wins this fight decisively, or if he wins a decision, he should finally start getting the respect he’s due.”